Vitamin B12, Thiamin, and Niacin in Mental Health Care

B12, thiamin, and niacin play many important roles in mental health.

Vitamin B12 is often recommended for elderly nondemented individuals who complain of impaired cognition; however, research findings are inconsistent. In a pilot study (N = 22), 18 elderly patients with abnormal low serum B12 levels and cognitive impairment were treated with B12 (1 mg per day intramuscularly) for 1 week, followed by weekly 1-mg injections for 1 month, then monthly 1-mg injections for 6 months. Patients who had been cognitively impaired for less than 1 year experienced significant improvement, whereas patients who had been impaired for longer than 1 year became worse, suggesting that supplementation may ameliorate symptoms related to B12 deficiency only in the early stages of cognitive impairment.

Chronic alcoholics are typically deficient in thiamin, folate, B6, and B12 because of toxic effects of alcohol on the mucosal lining of the stomach and small intestine. For individuals who are unable to remain abstinent, taking 2 g of vitamin C close to the time of alcohol consumption may reduce or prevent hangover symptoms by neutralizing metabolites of alcohol that cause oxidative damage to the body and brain.

Thiamin is essential for the metabolism of acetylcholine and its release from presynaptic neurons. Depressed patients report improved mood and energy with daily thiamin supplementation of 50 mg. When taken together with a conventional antipsychotic medication, 500 mg thrice daily of thiamin (vitamin B1) may lessen the severity of psychotic symptoms in patients with chronic schizophrenia. Thiamin-dependent enzymes may be abnormal in Alzheimer disease. Findings on high-dose thiamin (3 to 8 g per day) in Alzheimer disease are inconsistent. Animal studies suggest that low serum thiamin levels are associated with increased alcohol craving.

Niacin in the form of 1.25 g per day of nicotinamide taken with a meal before drinking may protect the liver against the acute toxic effects of alcohol in individuals who have relapsed. Early double-blind, RCTs reported that large doses of niacin (up to 3 to 8 g per day) ameliorated symptoms of schizophrenia. A combined regimen of high-dose niacin and a conventional antipsychotic medication reportedly resulted in differentially greater improvement in positive psychotic symptoms compared to schizophrenic patients treated with conventional antipsychotics alone. A subsequent review of 53 trials on niacin and other vitamins in the treatment of schizophrenia and other chronic psychiatric disorders identified methodological flaws in early studies and concluded that findings reached only marginal statistical significance. Nevertheless, high-dose niacin has become a standard therapy for schizophrenia in orthomolecular psychiatry, and case reports of dramatic outcomes continue to be published. A retrospective analysis of negative findings of controlled trials suggested that nonmedicated patients with schizophrenia in the early acute phase of illness may experience significant and sustained benefits from high doses of niacin, in contrast to medicated patients with schizophrenia or individuals in the chronic phase of the illness.

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